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This episode is sponsored by Dropbox.
Your body is about ⅔ water. Earth’s surface is about ⅔ oceans. This is not a coincidence.
All of our lives began in water. Every plant and animal living on dry land
today can trace its family tree back to the sea.
Each of us, in every salty cell of our bodies, are a bit of the ocean that grew legs, walked
up on shore and learned to build sports cars, skyscrapers, and spaceships.
But in taking over the land, we’ve put a lot of extra carbon in the air, and that’s
having serious effects on our climate. Much of that change isn’t happening in the
atmosphere. It’s in the oceans, and for one colorful group of creatures that could
spell disaster.
Coral reefs. Can they survive climate change?
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Animal. Vegetable. And mineral. Coral reefs are a little hard to classify, because, they’re
kind of all three. The animal bits come in the form of tiny invertebrates
called polyps, that use tentacled arms to feed on plankton and other small sea creatures.
But living inside each polyp are single-celled, plant-like algae. These can make up as much
as a third of the polyp’s body, and they’re what give coral reefs their colors.
These organisms have a sort of cooperative living arrangement called symbiosis.
During photosynthesis, the algae consumes the polyp’s waste CO2 and in return burps
out oxygen and nutrients to feed its host. The coral says thanks by giving the algae
a nice, safe place to live: inside its own body.
Together, massive colonies of these symbionts secrete calcium carbonate exoskeletons, building
up the multicolored megastructures that we call coral reefs.
Marine biologist Sylvia Earle called coral reefs the “jeweled belt around the middle
of the planet.” Because they rely on photosynthesis, we mostly
find ‘em anchored between the tropics, where Earth receives the most sunlight.
Unfortunately, thanks to the extra carbon dioxide and other greenhouse gases we’ve
pumped into the atmosphere, more and more of that sunlight’s heat is being trapped
in Earth’s atmosphere. But most of it hasn’t stayed there.
Since 1955, 90% of the atmosphere’s excess heat has been absorbed by the oceans.
And in addition to all that energy, it’s estimated that oceans have soaked up half
of all CO2 emissions since the industrial revolution.
And that's not like a bubbly soda, instead much of that CO2 gets chemically converted
into acid.
If climate change is stressing you out, you’re not alone.
These warm waters, acidic conditions and increased pollution are straining the delicate symbiotic
relationships between algae and their coral hosts, and many coral are kicking their colorful
roommates to the curb. Now, ejecting the algae leaves reefs looking
rather blah and colorless, so the phenomenon is called coral bleaching. Bleaching leaves
polyps without nutrients and susceptible to disease, and if it lasts long enough, the
coral will die.
Losing coral reefs would mean losing the most diverse ecosystems that our planet has to
offer. Even though they cover just a tenth of a percent
of the ocean floor, reefs provide a home to a quarter of all ocean species. In some tropical
reefs, a thousand different species can live in a single square meter.
In many places, this change already happening. Half of all tropical reefs have disappeared
in the past 30 years, and if the ocean continues to get warmer like it is today, coral may
die off completely by 2050. It’s reefer badness out there.
"Carl, Carl, Carl, Coral? Carl, Coral…"
Right now, we’re changing the planet faster than coral can adapt, but there is hope.
Some scientists from Australia and Hawaii have figured out how to breed coral in the
lab, and similar to how farmers cross plants to select for bigger fruit or drought resistance,
they think that they can accelerate the evolution of polyps and their algae accomplices to create
stress-resistant super coral.
We’ve changed a lot since our ancestors left the shore, but from the air we breathe
to the water within us, each of our lives is still connected to the ocean. Helping coral
will help us all.
That way, next time we take a visit to where we came from, looking for sea life, there
will still be life to see.
"Coral!"
If you want to learn more about climate science, we've got a bunch of other great videos here
on It's Okay To Be Smart, and coral is not the only thing being put at risk by our changing
climate. Check out the rest of the #OursToLose campaign and you'll find out a bunch of different
ways that climate change is already impacting all of our lives.
Stay curious.